remove "write protection"

Is this a company or your personal computer and USB drive?

Many companies are using policies and software to limit the ability to write files to unapproved removable media. If this is the case, the only way to remove the write protection is to contact company IT and get the USB device added to the list of approved devices.

In a similar vein, if the drive has encryption software installed, you may need to run the software on the drive and enter the proper password to be able to write files to the drive.

As far as I know, there is no inherent feature in Windows 7 that blocks writing to USB drives. The above items are the most likely cause of your issue.

Chas